There is a Simpsons episode in which Montgomery Burns comes clean as to the fate of Smithers' father, who years before died in an "accident" at the power plant, not at the hands of suspect Burns (or a tribe of savage women, for that matter). As he loads an old reel onto a film projector, Burns proclaims "if you see one film this year that proves my innocence, make it this one." Let me co-opt that sentiment for the new Sigur Rós compilation Hvarf/Heim: if you are to own one record that captures the raison d'etre of this Icelandic powerhouse, make it this one. This essential disc proficiently presents the forlorn beauty and fierce imagination of the volcanic isle's quintessential post-millennia band.

The seventy-plus minutes of music is in actuality two EPs. The title of the first, Hvarf, translates appropriately as "disappeared," as its five tracks are new recordings of lost songs from various points in Sigur Rós' history. An alternative translation of "Hvarf" is "haven," which ties into the title of the second portion of this release, Heim, or "home." Heim's six tracks are live acoustic versions of songs culled from all four of the band's studio albums, recorded in Iceland during the band's 2006 and 2007 tours. (The unplugged scenario had been pretty much imposed on the band, there being no power at some of the locations).

The first three songs from Hvarf - "Salka," "Hljomalind" and "I Gaer" -were never released, either because they had yet to be recorded or because they were recorded but then left on the cutting room floor. All three tracks are beautiful and simple compositions, steering within the lanes of the established Sigur Rós formula: pitched, indecipherable vocals, over a cascading accompaniment of fluid guitar and keys, soft drum and bass, and tasteful strings. The fourth and fifth, "Von" and perennial live favorite "Hafsol" respectively, are re-imaginings of songs from the band's first album, the original versions of which were recorded by members Jonsi Birgisson and Georg Holm with drummer Agust Gunnarsson, prior to Kjartan Sveinsson and Orri Dyrason joining the band. Whether the tracks are familiar from the debut matters not; the updated versions are disarmingly mature, stunning in their structural soul. Both could easily be off the group's impending fifth studio release, they sound that pristine.

At about the halfway mark, as Hvarf winds down, the listener is primed for Sigur Rós' unequaled primal splendor. Heim opens with the instantly recognizable instrumental "Untitled 3," from the band's third album, the cryptically titled (). Droning minor-keyed accordion notes give way to recurring major-key classical piano arpeggios, and it all spirals upward from there, like leaves rising in a plume of wind. This leads effortlessly into "Staralfur," and it is hard not to picture that magnificent scene in The Life Aquatic with Steve Zissou, in which the entire crew is in an underwater vessel, viewing the elusive tiger fish for the first time (it's an understatement that Wes Anderson knows how to score his films).

It's then back to tracks from () for that album's opener, the utterly heartrending (check the video) "Untitled 1." Though this is arguably one of their strongest "songs," the track also exemplifies why it is nearly impossible to think of Sigur Rós as typical songwriters. The group transcends the theoretical limitations of popular music; it's easy to see why they invent their own language, Hoplandic. Or how they re-define what it means to be a live rock band, as they comfortably employ a classical string quartet of women in formalwear on stage. The album closes with three more testaments to the bands' aural supremacy: "Heysatan" from Takk…, "Von" from their debut of the same name, and the title track from the band's sophomore masterwork, Ágćtis Byrjun, a song never performed live prior to last summer. Heim's stirring version of this piece of musical bliss alone is worth tracking this release down.

Looking back, I distinctly recall being momentarily confused upon my first encounter with Sigur Rós. Part of me thought they were just some new-age incarnation of Godspeed You! Black Emperor; yet, I was simultaneously pulled into their unique universe. After many more listens through the band's elegant discography, along with what could realistically be described as "elation" at seeing the band perform live on a small stage, I have firmly come to the same conclusions as music lovers far and wide: this group of young men from the land of geysers and glaciers possess the magic dust. They have blended the sensitivity of classical and the sensibility of rock into something far greater than post-rock. If "post" necessarily conjures up thoughts of leaving something behind, than Sigur Rós must be considered "pre." Whatever they are preceding is best left to the collective, ancient imaginations of their listeners; for this band does not alienate anything, they unite everything.